Posted
by
kdawson
on Monday March 05, 2007 @08:01PM
from the reflect-on-this dept.

QuantumCrypto writes "Researchers at Rensselaer Polytechnic Institute have created 'the world's first material that reflects virtually no light.' This anti-reflection technology is based on nanomaterial and could lead to the development of more efficient solar cells, brighter LEDs, and 'smarter' light sources. In theory, if a room were to be coated with this material, switching on the lights would only illuminate the items in the room and not the walls, giving a sense of floating free in infinite space."

The interesting thing about light is that it's NOT radar.
Maybe not, but they're both electromagnetic waves (though with a very different wavelength). So the question may be relevant.

It's not particularly relevant. The wavelength difference between radar and light is in the range of 20000 to one. You need two different antennas to pick up AM and FM, and they are only different by about two orders of magnitude (100:1). Dealing with electromagnetic radiation has everything to do with wavelength. A material "tuned" to absorb the maximum about of EM radiation between 400 and 700 nanometers wavelength is utterly unsuited to the task of absorbing radar at 1-4 centimeters. I'm not trying to be a troll here. I'm pointing out the science.

no, as a highschool student we have both goth and emo. The difference is goths are just like the same, goths havent changed, emo's on the other hand, are all about being pansy ass little pussies about everything and trying as hard as possible to look and act like emaciated little girls. Also the music is completely different, you cant even compair The Cruxshadows(really good band) to emo shit like falloutboy, panic at the disco, and the other "i hate my life and no one loves me bands"

I expect a very practical use for this material, if it is not too expensive, will be as a wall coating to replace green screens in filmmaking. It would allow lighting the subjects without worry about any light spill onto the background, and maybe allow better keying for special effects. You would just replace all pixel values that equal zero with your own background data, instead of keying on that narrow-band green which is, after all, still green.

except that would be color keying much harder because black naturally exists on objects like people and clothes. the reason things are shot again chroma green and blue is because they're not as commonly occurring in the objects that they're trying to photograph and extract. the reason the green and blue are a very specific color is to make keying easier by isolating that color in one channel of rgb. that way it's much easier to determine the differential information. keying against black is practically useless unfortunately. you'd have to go in and rotoscope everything that is black (like hair or eyeglass frames or belt, etc) or a value of black back in to the image. plus, on set they don't worry about light spilling onto the screen because they're usually much more brightly lit than the subject to keep a consistent tone throughout. presumeably, the reason they use blue and green is to allow for photography of subjects that are in the other color range (ie, guy with green shirt on bluescreen, guy with blueshirt on greenscreen). nobody keys against chroma red because obviously everyone's skin would cause them to be semi-transparent.

if you're talking about the key color spilling into the subject (like in between hair and such) than that's a different issue. that's why when you do a telecine, you'll do what's called a "suppress pass" which desaturated all of the key's color. that way you can comp the original footage minus the key color back into the comp to kill the color spill without having to hand-draw it into each frame.

i'm sure it could be used for some pretty interesting techniques in photography and film but color keying isn't likely to be one of them.

Like others have said, I don't know how well this would work; I think chromakey techniques (green or blue screens) are better (but because chroma keys are cleaner than luma keys, not because of the black problem); but your theory could work just fine under the right circumstances. I work in TV and have done keys just as you describe (though graphic keys, not people, but the concept is the same). With analog (composite) video, the blackest part of the picture should be 7.5% (IRE [wikipedia.org]) -- not 0; because of some boring complicated details related to using a 60-ish year old standard. If you use, say, 0 or 3 IRE as the part to be keyed out and leave the true black of the image at 7.5 IRE, you could easily set your switcher to key properly with the proper black levels. What you describe is called a Luma Key [wikipedia.org].
Now a lot of production is done digitally (SDI [wikipedia.org]), where the blacks are at 0%, so that makes it more complicated, but it might still work, though I haven't tried it.

It would allow lighting the subjects without worry about any light spill onto the background

A very interesting idea. There are plenty of times one wants exactly this effect and having walls like you describe might make it easier.